Mercedes-Benz C-Klasse W205
Weaknesses, engine ratings and buying advice
The C-Class W205 (2014–2021) was a quantum leap over the W204 — lighter (aluminium hybrid construction), more modern, far better interior. But the W205 has its own weaknesses, and the rust issue isn't entirely solved.
Engine choice: The OM651DE22 2.1 CDI in the C 220 d (125 kW, until 2018) is the proven diesel all-rounder. The M274 2.0 Turbo in the C 200/250/300 is the solid petrol — thermostat defects occur but are cheaply fixable. Avoid: The OM654 2.0 Diesel (C 220 d from mid-2018, C 300 d) has cracked timing chains regardless of maintenance — a serious risk. Enthusiast: M177 4.0 V8 BiTurbo in the AMG C 63/C 63 S — less iconic than the M156 predecessor but more liveable. Ignition coil failures between 60,000–100,000 km, boost leaks to watch.
Rust: The W205 also rusts on longitudinal members and rear subframe — less dramatic than the W204 but present. Front axle flags at MOT from the second inspection — control arm bushings, dampers, thrust arm rubber mounts. Battery drain during standstill: Keyless-Go door handles with moisture damage keep the system awake. A/C compressor fails ($550–2,200). Panoramic roof recall — trim can detach.
Cabriolet owners: Roof tension cables tear — repair $3,300–7,150 at the dealer. Water runs onto the driver's seat when opening the door with a wet roof — by design, not fixable.
Test-drive checklist: Underside for rust (longitudinal members, subframe). Switch on A/C — does the compressor rattle? Battery voltage at startup. Check panoramic roof recall by VIN. Suspension over cobblestones.
2026 market: Entry from $11,000. Reasonable examples (100–150k km) $17,600–24,200. Young used $24,200–38,500. AMG C 63 from $41,800, C 63 S from $49,500.
Insider pick: C 220 d (OM651, 2014–2018) with automatic — before the OM654 timing chain risk, proven diesel. Underside check and panoramic roof recall as purchase conditions.
510 PS
AMG C 63 S · Benzin
510 hp tail-happy — most uncompromising M177
Legendary!457–525 PS
6.2L V8 AMG Benzin
10 weaknesses
Stay Away!Body Variants
The Mercedes-Benz C-Klasse W205 is available as Sedan and T-Modell — choose your body type for specific insurance data:
Generations
Engine Overview
The Mercedes-Benz C-Klasse W205 is available with 27 engine variants — from 90 to 612 hp. 3 variants had engine changes — the model year is crucial.
Smaller displacement variant of the OM651. Same technology as the 2.1L but less torque. Known for injector seal issues and timing chain stretch.
- !! Piezo Injector Faults (220/250 CDI) from 80,000 km
Quality issues with Delphi piezo injectors in the 220 CDI and 250 CDI: injectors fail prematurely. A service action replaced piezo injectors with solenoid injectors free of charge.
Symptoms: Strong vibrations under acceleration, rough running, elevated fuel consumption, exhaust smoke - !! Chain Tensioner Failure with Oil Loss from 120,000 km
The OM651 chain tensioner can fail and allow engine oil to escape. Mainly affects vehicles built February–November 2014 (recall). Simplex roller chain increases wear risk.
Symptoms: Light rattling on cold start from the rear of the engine, oil loss, engine warning light - !! Particulate Filter Blockage with Short-Trip Use from 100,000 km
The DPF on the OM651DE18 does not regenerate completely during pure short-trip driving and blocks. A motorway run at least every 2 weeks is required.
Symptoms: DPF warning light, power reduction, engine oil diluted by unburnt fuel
+ 2 more engine weaknesses + vehicle weaknesses
Widely used Mercedes diesel with aluminium block and steel liner. High mileages possible but known for injector seal issues, timing chain stretch and EGR problems.
- !! Chain Tensioner Seal Leaking — Recall
Over 100,000 vehicles recalled: the chain tensioner seal leaks, allowing engine oil to drip onto the exhaust system and potentially ignite.
Symptoms: Dropping oil level, oil smell from engine bay, oily deposits under the vehicle, possible oil fire - !! Timing Chain Stretch (Simplex Chain) from 150,000 km
The OM651 uses a simplex timing chain. With short-trip driving and overdue oil change intervals the chain stretches.
Symptoms: Light rattling noise on cold start from the rear of the engine, no fault code stored - !! Piezo Injector Faults from 80,000 km
Same Delphi piezo injector problems as in the DE18: 220 CDI and 250 CDI variants affected. Mercedes replaced them with solenoid injectors as part of a service action.
Symptoms: Vibrations and rough running especially under acceleration, elevated fuel consumption
+ 3 more engine weaknesses + vehicle weaknesses
Renault-based small diesel, new generation. Economical with SCR catalyst, but still with little power reserve. Automatic only.
- !! Timing belt maintenance obligation from 120,000 km
Like its Renault counterpart, the OM608 uses a timing belt. Prescribed change every 120,000 km or 6 years -- frequently forgotten as Mercedes buyers are accustomed to timing chains.
Symptoms: No warning on snap -- sudden engine failure and severe engine damage - !! Timing belt change critical from 120,000 km
The OM608 (Renault K9K base) uses a timing belt. Mercedes specifies 200,000 km change interval; Renault prescribes 120,000 km for the same engine. A snap causes immediate total damage on this interference engine.
Symptoms: No noticeable warning before snap; beforehand: faint squealing, occasionally starting difficulties - !! Increased oil consumption / turbo shaft seal from 100,000 km
The Renault-based OM608 1.5 CDI sometimes shows increased oil consumption from early on due to a leaking turbocharger shaft seal. Oil mist in the intake tract behind the turbo.
Symptoms: Dropping oil level, oil mist or blue smoke from exhaust, oil in air filter housing behind turbo
+ 2 more engine weaknesses + vehicle weaknesses
Smaller displacement variant of the OM651. Same technology as the 2.1L but less torque. Known for injector seal issues and timing chain stretch.
- !! Piezo Injector Faults (220/250 CDI) from 80,000 km
Quality issues with Delphi piezo injectors in the 220 CDI and 250 CDI: injectors fail prematurely. A service action replaced piezo injectors with solenoid injectors free of charge.
Symptoms: Strong vibrations under acceleration, rough running, elevated fuel consumption, exhaust smoke - !! Chain Tensioner Failure with Oil Loss from 120,000 km
The OM651 chain tensioner can fail and allow engine oil to escape. Mainly affects vehicles built February–November 2014 (recall). Simplex roller chain increases wear risk.
Symptoms: Light rattling on cold start from the rear of the engine, oil loss, engine warning light - !! Particulate Filter Blockage with Short-Trip Use from 100,000 km
The DPF on the OM651DE18 does not regenerate completely during pure short-trip driving and blocks. A motorway run at least every 2 weeks is required.
Symptoms: DPF warning light, power reduction, engine oil diluted by unburnt fuel
+ 2 more engine weaknesses + vehicle weaknesses
Widely used Mercedes diesel with aluminium block and steel liner. High mileages possible but known for injector seal issues, timing chain stretch and EGR problems.
- !! Chain Tensioner Seal Leaking — Recall
Over 100,000 vehicles recalled: the chain tensioner seal leaks, allowing engine oil to drip onto the exhaust system and potentially ignite.
Symptoms: Dropping oil level, oil smell from engine bay, oily deposits under the vehicle, possible oil fire - !! Timing Chain Stretch (Simplex Chain) from 150,000 km
The OM651 uses a simplex timing chain. With short-trip driving and overdue oil change intervals the chain stretches.
Symptoms: Light rattling noise on cold start from the rear of the engine, no fault code stored - !! Piezo Injector Faults from 80,000 km
Same Delphi piezo injector problems as in the DE18: 220 CDI and 250 CDI variants affected. Mercedes replaced them with solenoid injectors as part of a service action.
Symptoms: Vibrations and rough running especially under acceleration, elevated fuel consumption
+ 3 more engine weaknesses + vehicle weaknesses
Widely used Mercedes diesel with aluminium block and steel liner. High mileages possible but known for injector seal issues, timing chain stretch and EGR problems.
- !! Chain Tensioner Seal Leaking — Recall
Over 100,000 vehicles recalled: the chain tensioner seal leaks, allowing engine oil to drip onto the exhaust system and potentially ignite.
Symptoms: Dropping oil level, oil smell from engine bay, oily deposits under the vehicle, possible oil fire - !! Timing Chain Stretch (Simplex Chain) from 150,000 km
The OM651 uses a simplex timing chain. With short-trip driving and overdue oil change intervals the chain stretches.
Symptoms: Light rattling noise on cold start from the rear of the engine, no fault code stored - !! Piezo Injector Faults from 80,000 km
Same Delphi piezo injector problems as in the DE18: 220 CDI and 250 CDI variants affected. Mercedes replaced them with solenoid injectors as part of a service action.
Symptoms: Vibrations and rough running especially under acceleration, elevated fuel consumption
+ 3 more engine weaknesses + vehicle weaknesses
Completely new aluminium diesel with NANOSLIDE coating and integrated particulate filter. Noticeably quieter and cleaner than the OM651. Few typical faults known to date.
- !! Rocker Arm and Camshaft Wear from 80,000 km
Known weak point: the narrow camshaft lobes and rocker arms in the OM654 wear prematurely due to inadequate lubrication. Mercedes issued TSBs.
Symptoms: Ticking or knocking from engine bay, misfires, rough running, engine warning light - !! Electric Coolant Pump Leaking — Recall
Over 800,000 Mercedes diesel vehicles with OM654/OM656 were recalled due to a leaking electric coolant pump. Coolant loss can lead to overheating.
Symptoms: Coolant loss, overheating warning, coolant warning light, engine temperature rises - !! NOx Sensor Defective — AdBlue Fault and Start Inhibit from 90,000 km
NOx sensors wear out from soot particles and deliver erroneous readings. Consequence: incorrect AdBlue injection, CEL illumination; if unaddressed, an engine start inhibit may follow. Both sensors can be affected.
Symptoms: CEL, AdBlue warning, fault code P20EE or P204F, message 'No start after X km', rough idle
+ 8 more engine weaknesses + vehicle weaknesses
Widely used Mercedes diesel with aluminium block and steel liner. High mileages possible but known for injector seal issues, timing chain stretch and EGR problems.
- !! Chain Tensioner Seal Leaking — Recall
Over 100,000 vehicles recalled: the chain tensioner seal leaks, allowing engine oil to drip onto the exhaust system and potentially ignite.
Symptoms: Dropping oil level, oil smell from engine bay, oily deposits under the vehicle, possible oil fire - !! Timing Chain Stretch (Simplex Chain) from 150,000 km
The OM651 uses a simplex timing chain. With short-trip driving and overdue oil change intervals the chain stretches.
Symptoms: Light rattling noise on cold start from the rear of the engine, no fault code stored - !! Piezo Injector Faults from 80,000 km
Same Delphi piezo injector problems as in the DE18: 220 CDI and 250 CDI variants affected. Mercedes replaced them with solenoid injectors as part of a service action.
Symptoms: Vibrations and rough running especially under acceleration, elevated fuel consumption
+ 3 more engine weaknesses + vehicle weaknesses
Completely new aluminium diesel with NANOSLIDE coating and integrated particulate filter. Noticeably quieter and cleaner than the OM651. Few typical faults known to date.
- !! Rocker Arm and Camshaft Wear from 80,000 km
Known weak point: the narrow camshaft lobes and rocker arms in the OM654 wear prematurely due to inadequate lubrication. Mercedes issued TSBs.
Symptoms: Ticking or knocking from engine bay, misfires, rough running, engine warning light - !! Electric Coolant Pump Leaking — Recall
Over 800,000 Mercedes diesel vehicles with OM654/OM656 were recalled due to a leaking electric coolant pump. Coolant loss can lead to overheating.
Symptoms: Coolant loss, overheating warning, coolant warning light, engine temperature rises - !! NOx Sensor Defective — AdBlue Fault and Start Inhibit from 90,000 km
NOx sensors wear out from soot particles and deliver erroneous readings. Consequence: incorrect AdBlue injection, CEL illumination; if unaddressed, an engine start inhibit may follow. Both sensors can be affected.
Symptoms: CEL, AdBlue warning, fault code P20EE or P204F, message 'No start after X km', rough idle
+ 8 more engine weaknesses + vehicle weaknesses
Completely new aluminium diesel with NANOSLIDE coating and integrated particulate filter. Noticeably quieter and cleaner than the OM651. Few typical faults known to date.
- !! Rocker Arm and Camshaft Wear from 80,000 km
Known weak point: the narrow camshaft lobes and rocker arms in the OM654 wear prematurely due to inadequate lubrication. Mercedes issued TSBs.
Symptoms: Ticking or knocking from engine bay, misfires, rough running, engine warning light - !! Electric Coolant Pump Leaking — Recall
Over 800,000 Mercedes diesel vehicles with OM654/OM656 were recalled due to a leaking electric coolant pump. Coolant loss can lead to overheating.
Symptoms: Coolant loss, overheating warning, coolant warning light, engine temperature rises - !! NOx Sensor Defective — AdBlue Fault and Start Inhibit from 90,000 km
NOx sensors wear out from soot particles and deliver erroneous readings. Consequence: incorrect AdBlue injection, CEL illumination; if unaddressed, an engine start inhibit may follow. Both sensors can be affected.
Symptoms: CEL, AdBlue warning, fault code P20EE or P204F, message 'No start after X km', rough idle
+ 8 more engine weaknesses + vehicle weaknesses
Four-valve V6 in two basic variants: 3.5L naturally aspirated (DES 35, 185–225 kW) with direct injection and stratified charge — refined, linear, no classic naturally aspirated feel. And the 3.0L BiTurbo family (DEH 30 LA, 245–295 kW) with Nanoslide coating, twin turbochargers and water-air charge air cooler. The BiTurbo sings sonorously from 2,500 rpm and screams at the top — exceptional for a V6. Weak points: timing chain wears early when oil change intervals are pushed. Oil cooler in the V-block doesn't seal forever. Camshaft solenoids leak. On the 3.5L stratified-charge variant add NOx sensor failures from short-trip use. Early DES 35 (2011–2013) had piston slap issues. The BiTurbo unit with Nanoslide is considered more robust. Maintained with short oil change intervals (10,000–12,000 km) the engine easily lasts beyond 200,000 km.
- !! Oil cooler leaking in the V-block from 120,000 km
Known weak point: the oil cooler gasket in the V-block of the M276 ages and starts leaking. Repair is extremely labour-intensive because the engine must be partially disassembled — cost €1,700–3,800.
Symptoms: Oil spots under the vehicle, rainbow sheen on wet road, dropping oil level, oil smell - !! Camshaft adjuster leaking — wiring harness contaminated from 100,000 km
Known damage pattern on all newer Mercedes engines: solenoid valves leak, oil migrates into the wiring harness. First the lambda sensors die, then the ECU. Repair documented up to €1,970.
Symptoms: Check engine light with camshaft fault code, lambda sensor failure, oil film on connectors, in extreme cases ECU failure - !! Piston slap (early 3.5L variants) from 150,000 km
On early M276 DES 35 (build years 2011–2013) pistons can loosen due to cylinder bore wear. Knock noise on cold start, worst case engine damage.
Symptoms: Clacking and knocking on cold start from the engine area, getting louder over time, rough idle when cold
+ 7 more engine weaknesses + vehicle weaknesses
Four-valve V6 in two basic variants: 3.5L naturally aspirated (DES 35, 185–225 kW) with direct injection and stratified charge — refined, linear, no classic naturally aspirated feel. And the 3.0L BiTurbo family (DEH 30 LA, 245–295 kW) with Nanoslide coating, twin turbochargers and water-air charge air cooler. The BiTurbo sings sonorously from 2,500 rpm and screams at the top — exceptional for a V6. Weak points: timing chain wears early when oil change intervals are pushed. Oil cooler in the V-block doesn't seal forever. Camshaft solenoids leak. On the 3.5L stratified-charge variant add NOx sensor failures from short-trip use. Early DES 35 (2011–2013) had piston slap issues. The BiTurbo unit with Nanoslide is considered more robust. Maintained with short oil change intervals (10,000–12,000 km) the engine easily lasts beyond 200,000 km.
- !! Oil cooler leaking in the V-block from 120,000 km
Known weak point: the oil cooler gasket in the V-block of the M276 ages and starts leaking. Repair is extremely labour-intensive because the engine must be partially disassembled — cost €1,700–3,800.
Symptoms: Oil spots under the vehicle, rainbow sheen on wet road, dropping oil level, oil smell - !! Camshaft adjuster leaking — wiring harness contaminated from 100,000 km
Known damage pattern on all newer Mercedes engines: solenoid valves leak, oil migrates into the wiring harness. First the lambda sensors die, then the ECU. Repair documented up to €1,970.
Symptoms: Check engine light with camshaft fault code, lambda sensor failure, oil film on connectors, in extreme cases ECU failure - !! Piston slap (early 3.5L variants) from 150,000 km
On early M276 DES 35 (build years 2011–2013) pistons can loosen due to cylinder bore wear. Knock noise on cold start, worst case engine damage.
Symptoms: Clacking and knocking on cold start from the engine area, getting louder over time, rough idle when cold
+ 7 more engine weaknesses + vehicle weaknesses
The M177 is AMG's most widely used V8 biturbo today and is considered technically mature and long-lived. The hot-V turbocharger arrangement delivers spontaneous response with barely perceptible lag. Weaknesses are manageable: wastegate rattle in cold weather, ignition coil recall for early 2015 model years, valve cover gaskets with age. Regular oil changes with attention to oil quality deliver a very robust engine. In direct comparison with the M156 less emotional, but significantly more reliable and efficient.
- !! MCT Gearbox — Clutch Wears in City Traffic from 60,000 km
The MCT Speedshift gearbox (wet launch clutch instead of torque converter) wears the clutch significantly faster in frequent stop-and-go. Clutch replacement requires gearbox removal.
Symptoms: Judder on pull-away, clutch slip at full load, gearbox warning message, delayed engagement from standstill - !! Camshaft Adjuster Solenoid Draws Oil into Wiring Harness from 70,000 km
Identical issue to the M176/M278: the solenoid leaks, oil migrates by capillary action through the wiring harness. On AMG vehicles this is even more frequent due to higher oil temperatures.
Symptoms: Cold-start rattle, camshaft adjuster fault code, oil traces on connector, potential ECU consequential damage - !! Camshaft Cover Gasket Leaking — Hot-V Area from 60,000 km
The camshaft cover gaskets on the M177 AMG V8 become brittle from the high heat exposure in the hot-V. Oil escapes onto turbochargers and exhaust system.
Symptoms: Oil smell on hot engine, oil film on turbochargers, smoke from engine bay
+ 5 more engine weaknesses + vehicle weaknesses
The M177 is AMG's most widely used V8 biturbo today and is considered technically mature and long-lived. The hot-V turbocharger arrangement delivers spontaneous response with barely perceptible lag. Weaknesses are manageable: wastegate rattle in cold weather, ignition coil recall for early 2015 model years, valve cover gaskets with age. Regular oil changes with attention to oil quality deliver a very robust engine. In direct comparison with the M156 less emotional, but significantly more reliable and efficient.
- !! MCT Gearbox — Clutch Wears in City Traffic from 60,000 km
The MCT Speedshift gearbox (wet launch clutch instead of torque converter) wears the clutch significantly faster in frequent stop-and-go. Clutch replacement requires gearbox removal.
Symptoms: Judder on pull-away, clutch slip at full load, gearbox warning message, delayed engagement from standstill - !! Camshaft Adjuster Solenoid Draws Oil into Wiring Harness from 70,000 km
Identical issue to the M176/M278: the solenoid leaks, oil migrates by capillary action through the wiring harness. On AMG vehicles this is even more frequent due to higher oil temperatures.
Symptoms: Cold-start rattle, camshaft adjuster fault code, oil traces on connector, potential ECU consequential damage - !! Camshaft Cover Gasket Leaking — Hot-V Area from 60,000 km
The camshaft cover gaskets on the M177 AMG V8 become brittle from the high heat exposure in the hot-V. Oil escapes onto turbochargers and exhaust system.
Symptoms: Oil smell on hot engine, oil film on turbochargers, smoke from engine bay
+ 5 more engine weaknesses + vehicle weaknesses
The M177 is AMG's most widely used V8 biturbo today and is considered technically mature and long-lived. The hot-V turbocharger arrangement delivers spontaneous response with barely perceptible lag. Weaknesses are manageable: wastegate rattle in cold weather, ignition coil recall for early 2015 model years, valve cover gaskets with age. Regular oil changes with attention to oil quality deliver a very robust engine. In direct comparison with the M156 less emotional, but significantly more reliable and efficient.
- !! MCT Gearbox — Clutch Wears in City Traffic from 60,000 km
The MCT Speedshift gearbox (wet launch clutch instead of torque converter) wears the clutch significantly faster in frequent stop-and-go. Clutch replacement requires gearbox removal.
Symptoms: Judder on pull-away, clutch slip at full load, gearbox warning message, delayed engagement from standstill - !! Camshaft Adjuster Solenoid Draws Oil into Wiring Harness from 70,000 km
Identical issue to the M176/M278: the solenoid leaks, oil migrates by capillary action through the wiring harness. On AMG vehicles this is even more frequent due to higher oil temperatures.
Symptoms: Cold-start rattle, camshaft adjuster fault code, oil traces on connector, potential ECU consequential damage - !! Camshaft Cover Gasket Leaking — Hot-V Area from 60,000 km
The camshaft cover gaskets on the M177 AMG V8 become brittle from the high heat exposure in the hot-V. Oil escapes onto turbochargers and exhaust system.
Symptoms: Oil smell on hot engine, oil film on turbochargers, smoke from engine bay
+ 5 more engine weaknesses + vehicle weaknesses
The M177 is AMG's most widely used V8 biturbo today and is considered technically mature and long-lived. The hot-V turbocharger arrangement delivers spontaneous response with barely perceptible lag. Weaknesses are manageable: wastegate rattle in cold weather, ignition coil recall for early 2015 model years, valve cover gaskets with age. Regular oil changes with attention to oil quality deliver a very robust engine. In direct comparison with the M156 less emotional, but significantly more reliable and efficient.
- !! MCT Gearbox — Clutch Wears in City Traffic from 60,000 km
The MCT Speedshift gearbox (wet launch clutch instead of torque converter) wears the clutch significantly faster in frequent stop-and-go. Clutch replacement requires gearbox removal.
Symptoms: Judder on pull-away, clutch slip at full load, gearbox warning message, delayed engagement from standstill - !! Camshaft Adjuster Solenoid Draws Oil into Wiring Harness from 70,000 km
Identical issue to the M176/M278: the solenoid leaks, oil migrates by capillary action through the wiring harness. On AMG vehicles this is even more frequent due to higher oil temperatures.
Symptoms: Cold-start rattle, camshaft adjuster fault code, oil traces on connector, potential ECU consequential damage - !! Camshaft Cover Gasket Leaking — Hot-V Area from 60,000 km
The camshaft cover gaskets on the M177 AMG V8 become brittle from the high heat exposure in the hot-V. Oil escapes onto turbochargers and exhaust system.
Symptoms: Oil smell on hot engine, oil film on turbochargers, smoke from engine bay
+ 5 more engine weaknesses + vehicle weaknesses
Modular four-cylinder turbo of the first compact platform generation. Known for timing chain stretch and thermostat issues. Adequate power up to 156 hp.
- !! Camshaft Adjuster Solenoid Leaks — Oil in Wiring Harness from 90,000 km
The sealing ring on the camshaft adjuster solenoid fails. Oil creeps by capillary action through the wiring harness and destroys lambda sensors and the ECU. Repair €1,700–€4,000.
Symptoms: Lambda sensor fault codes, engine stumbling, CEL. In later stages multiple electrical faults simultaneously, ECU coated with oil - !! Recall — Camshaft Break (Production Defect 2015)
M270 engines with manufacturing date July–September 2015 have a defective weld seam on the camshaft lobe. Camshaft can break → engine damage. Recall with free replacement.
Symptoms: Sudden engine noise, power loss up to engine stall. Only vehicles with production date July–September 2015 affected - !! Electric Thermostat Failure from 90,000 km
The electrically-controlled thermostat on the M270 fails frequently and is difficult to access at the rear of the engine. Replacement costs 800–1,300 EUR at Mercedes workshops.
Symptoms: Engine does not reach operating temperature of 80°C, coolant temperature fluctuates, fault code P0128
+ 4 more engine weaknesses + vehicle weaknesses
Modular four-cylinder turbo of the first compact platform generation. Known for timing chain stretch and thermostat issues. Adequate power up to 156 hp.
- !! Camshaft Adjuster Solenoid Leaks — Oil in Wiring Harness from 90,000 km
The sealing ring on the camshaft adjuster solenoid fails. Oil creeps by capillary action through the wiring harness and destroys lambda sensors and the ECU. Repair €1,700–€4,000.
Symptoms: Lambda sensor fault codes, engine stumbling, CEL. In later stages multiple electrical faults simultaneously, ECU coated with oil - !! Recall — Camshaft Break (Production Defect 2015)
M270 engines with manufacturing date July–September 2015 have a defective weld seam on the camshaft lobe. Camshaft can break → engine damage. Recall with free replacement.
Symptoms: Sudden engine noise, power loss up to engine stall. Only vehicles with production date July–September 2015 affected - !! Electric Thermostat Failure from 90,000 km
The electrically-controlled thermostat on the M270 fails frequently and is difficult to access at the rear of the engine. Replacement costs 800–1,300 EUR at Mercedes workshops.
Symptoms: Engine does not reach operating temperature of 80°C, coolant temperature fluctuates, fault code P0128
+ 4 more engine weaknesses + vehicle weaknesses
Modular four-cylinder turbo of the first compact platform generation. Known for timing chain stretch and thermostat issues. Adequate power up to 156 hp.
- !! Camshaft Adjuster Solenoid Leaks — Oil in Wiring Harness from 90,000 km
The sealing ring on the camshaft adjuster solenoid fails. Oil creeps by capillary action through the wiring harness and destroys lambda sensors and the ECU. Repair €1,700–€4,000.
Symptoms: Lambda sensor fault codes, engine stumbling, CEL. In later stages multiple electrical faults simultaneously, ECU coated with oil - !! Recall — Camshaft Break (Production Defect 2015)
M270 engines with manufacturing date July–September 2015 have a defective weld seam on the camshaft lobe. Camshaft can break → engine damage. Recall with free replacement.
Symptoms: Sudden engine noise, power loss up to engine stall. Only vehicles with production date July–September 2015 affected - !! Electric Thermostat Failure from 90,000 km
The electrically-controlled thermostat on the M270 fails frequently and is difficult to access at the rear of the engine. Replacement costs 800–1,300 EUR at Mercedes workshops.
Symptoms: Engine does not reach operating temperature of 80°C, coolant temperature fluctuates, fault code P0128
+ 4 more engine weaknesses + vehicle weaknesses
Modular four-cylinder turbo of the first compact platform generation. Known for timing chain stretch and thermostat issues. Adequate power up to 156 hp.
- !! Camshaft Adjuster Solenoid Leaks — Oil in Wiring Harness from 90,000 km
The sealing ring on the camshaft adjuster solenoid fails. Oil creeps by capillary action through the wiring harness and destroys lambda sensors and the ECU. Repair €1,700–€4,000.
Symptoms: Lambda sensor fault codes, engine stumbling, CEL. In later stages multiple electrical faults simultaneously, ECU coated with oil - !! Recall — Camshaft Break (Production Defect 2015)
M270 engines with manufacturing date July–September 2015 have a defective weld seam on the camshaft lobe. Camshaft can break → engine damage. Recall with free replacement.
Symptoms: Sudden engine noise, power loss up to engine stall. Only vehicles with production date July–September 2015 affected - !! Electric Thermostat Failure from 90,000 km
The electrically-controlled thermostat on the M270 fails frequently and is difficult to access at the rear of the engine. Replacement costs 800–1,300 EUR at Mercedes workshops.
Symptoms: Engine does not reach operating temperature of 80°C, coolant temperature fluctuates, fault code P0128
+ 4 more engine weaknesses + vehicle weaknesses
Modular four-cylinder turbo of the first compact platform generation. Known for timing chain stretch and thermostat issues. Adequate power up to 156 hp.
- !! Camshaft Adjuster Solenoid Leaks — Oil in Wiring Harness from 90,000 km
The sealing ring on the camshaft adjuster solenoid fails. Oil creeps by capillary action through the wiring harness and destroys lambda sensors and the ECU. Repair €1,700–€4,000.
Symptoms: Lambda sensor fault codes, engine stumbling, CEL. In later stages multiple electrical faults simultaneously, ECU coated with oil - !! Recall — Camshaft Break (Production Defect 2015)
M270 engines with manufacturing date July–September 2015 have a defective weld seam on the camshaft lobe. Camshaft can break → engine damage. Recall with free replacement.
Symptoms: Sudden engine noise, power loss up to engine stall. Only vehicles with production date July–September 2015 affected - !! Electric Thermostat Failure from 90,000 km
The electrically-controlled thermostat on the M270 fails frequently and is difficult to access at the rear of the engine. Replacement costs 800–1,300 EUR at Mercedes workshops.
Symptoms: Engine does not reach operating temperature of 80°C, coolant temperature fluctuates, fault code P0128
+ 4 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Four-cylinder turbo with 48V belt starter-generator. Modern, efficient engine with EQ Boost mild hybrid. Timing chain long-lived.
- !! Exhaust Valves Defective — Cylinder Head Damage (Serial Defect) from 60,000 km
Defective exhaust valves and soft valve guides lead to severe cylinder head damage. Often just after the warranty expires. Mercedes USA extended the warranty to 15 years/150,000 miles.
Symptoms: Sudden severe misfires, CEL flashing, power drop, dangerous stalling at motorway speed - !! HV Cables and E-Motor Integration Defective (PHEV) from 60,000 km
The electric motor is integrated into the 9G-Tronic. With faults in the high-voltage cables the gearbox must be removed — extremely costly repair.
Symptoms: Fault message 'Hybrid drivetrain disturbed', no electric drive possible, vehicle runs as pure combustion engine only, sometimes emergency shutdown - !! Chain Tensioner Loses Tension — Chain Rattling from 80,000 km
The hydraulic chain tensioner on the M264 can lose oil pressure after extended standstill. On cold start the timing chain rattles briefly until oil pressure builds.
Symptoms: Brief rattling on cold start (2–5 seconds), disappears after warm-up
+ 9 more engine weaknesses + vehicle weaknesses
Modern turbocharged four-cylinder with direct injection and piezo injectors. Successor to the M271. Less susceptible to timing chain issues. Good balance of power and economy.
- !! High-Pressure Pump Faulty or Noisy from 120,000 km
The high-pressure fuel pump on the M274 is driven by a lobe on the intake camshaft. Wear on the drive lobe or pump follower leads to pressure drop.
Symptoms: Metallic ticking from engine area, starting problems or extended cranking, power loss, fault code P0087 - !! Camshaft Adjuster Leaks — Oil in Wiring Harness from 100,000 km
On the M274 too, the camshaft adjuster solenoids develop leaks. Oil penetrates the wiring harness by capillary action and can damage the engine ECU.
Symptoms: Fault code P0010, CEL, oil traces at camshaft connectors, lambda sensor failure, in severe cases ECU failure - !! Electric thermostat failure from 100,000 km
Primary weak point of the M274: the electric thermostat sits deep in the engine block and is hard to reach. Replacement takes around 3 hours.
Symptoms: Engine does not reach operating temperature or overheats, temperature fluctuations, fault codes P0597–P0599
+ 3 more engine weaknesses + vehicle weaknesses
Four-valve V6 in two basic variants: 3.5L naturally aspirated (DES 35, 185–225 kW) with direct injection and stratified charge — refined, linear, no classic naturally aspirated feel. And the 3.0L BiTurbo family (DEH 30 LA, 245–295 kW) with Nanoslide coating, twin turbochargers and water-air charge air cooler. The BiTurbo sings sonorously from 2,500 rpm and screams at the top — exceptional for a V6. Weak points: timing chain wears early when oil change intervals are pushed. Oil cooler in the V-block doesn't seal forever. Camshaft solenoids leak. On the 3.5L stratified-charge variant add NOx sensor failures from short-trip use. Early DES 35 (2011–2013) had piston slap issues. The BiTurbo unit with Nanoslide is considered more robust. Maintained with short oil change intervals (10,000–12,000 km) the engine easily lasts beyond 200,000 km.
- !! Oil cooler leaking in the V-block from 120,000 km
Known weak point: the oil cooler gasket in the V-block of the M276 ages and starts leaking. Repair is extremely labour-intensive because the engine must be partially disassembled — cost €1,700–3,800.
Symptoms: Oil spots under the vehicle, rainbow sheen on wet road, dropping oil level, oil smell - !! Camshaft adjuster leaking — wiring harness contaminated from 100,000 km
Known damage pattern on all newer Mercedes engines: solenoid valves leak, oil migrates into the wiring harness. First the lambda sensors die, then the ECU. Repair documented up to €1,970.
Symptoms: Check engine light with camshaft fault code, lambda sensor failure, oil film on connectors, in extreme cases ECU failure - !! Piston slap (early 3.5L variants) from 150,000 km
On early M276 DES 35 (build years 2011–2013) pistons can loosen due to cylinder bore wear. Knock noise on cold start, worst case engine damage.
Symptoms: Clacking and knocking on cold start from the engine area, getting louder over time, rough idle when cold
+ 7 more engine weaknesses + vehicle weaknesses
Vehicle Weaknesses
| Weakness | Cost | |
|---|---|---|
| Rust on longitudinal members and rear axle subframe Longitudinal members, jack-point attachment holes and rear axle subframe rust through. MB offers goodwill replacement. Symptoms: Visible rust on underbody, MOT advisory on longitudinal members, corroded jacking points from 100,000 km | High |
Test Reports
TÜV Report 2024
The W205 impresses with low fault rates and repeatedly takes top positions in the MOT report for the mid-range class.
2023-11ADAC Breakdown Statistics 2024
The W205 is consistently the most reliable vehicle in the mid-range class across several years and regularly achieves class victory.
2024-04Top Reported Issues
Alternatives
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Known Problems and Issues +
A total of 96 weaknesses have been documented for the Mercedes-Benz C-Klasse W205 (2014–2021) — 80 engine-related and 16 vehicle-related. 2 problem engines: OM651DE22 (2.1L Diesel), M156 (6.2L V8 AMG). Typical issues affect Rust, Suspension, Electronics, Other.
C-Klasse (OM651DE18, 2014–2018) — Be Careful: Piezo Injector Faults (220/250 CDI), Chain Tensioner Failure with Oil Loss, Particulate Filter Blockage with Short-Trip Use. Power: 116–122 PS.
C-Klasse (OM651DE18, 2014–2017) — Be Careful: Piezo Injector Faults (220/250 CDI), Chain Tensioner Failure with Oil Loss, Particulate Filter Blockage with Short-Trip Use. Power: 136 PS.
C-Klasse (OM651DE22, 2014–2018) — Stay Away!: Chain Tensioner Seal Leaking — Recall, Timing Chain Stretch (Simplex Chain), Piezo Injector Faults. Power: 120 PS.
C-Klasse (OM651DE22, 2014–2018) — Stay Away!: Chain Tensioner Seal Leaking — Recall, Timing Chain Stretch (Simplex Chain), Piezo Injector Faults. Power: 136 PS.
C-Klasse (OM651DE22, 2014–2018) — Stay Away!: Chain Tensioner Seal Leaking — Recall, Timing Chain Stretch (Simplex Chain), Piezo Injector Faults. Power: 163–170 PS.
C-Klasse (OM651DE22, 2014–2018) — Stay Away!: Chain Tensioner Seal Leaking — Recall, Timing Chain Stretch (Simplex Chain), Piezo Injector Faults. Power: 204 PS.
C-Klasse (OM608, 2018–2021) — Be Careful: Timing belt maintenance obligation, Timing belt change critical, Increased oil consumption / turbo shaft seal. Power: 116–122 PS.
C-Klasse (OM654, 2018–2021) — Be Careful: Rocker Arm and Camshaft Wear, Electric Coolant Pump Leaking — Recall, NOx Sensor Defective — AdBlue Fault and Start Inhibit. Power: 194–200 PS.
C-Klasse (OM654, 2018–2021) — Be Careful: Rocker Arm and Camshaft Wear, Electric Coolant Pump Leaking — Recall, NOx Sensor Defective — AdBlue Fault and Start Inhibit. Power: 245 PS.
C-Klasse (M156, 2011–2015) — Stay Away!: Head Bolt Corrosion — Coolant in Combustion Chamber, Camshaft Wear — Cold-Start Lubrication Deficit, Camshaft Adjuster — Locking Plate Wears Out. Power: 457 PS.
C-Klasse (M156, 2011–2015) — Stay Away!: Head Bolt Corrosion — Coolant in Combustion Chamber, Camshaft Wear — Cold-Start Lubrication Deficit, Camshaft Adjuster — Locking Plate Wears Out. Power: 481–487 PS.
C-Klasse (M276, 2011–2015) — Be Careful: Oil cooler leaking in the V-block, Camshaft adjuster leaking — wiring harness contaminated, Piston slap (early 3.5L variants). Power: 306 PS.
C-Klasse (M270DE16, 2014–2018) — Be Careful: Camshaft Adjuster Solenoid Leaks — Oil in Wiring Harness, Recall — Camshaft Break (Production Defect 2015), Electric Thermostat Failure. Power: 156 PS.
C-Klasse (M274, 2014–2018) — Be Careful: High-Pressure Pump Faulty or Noisy, Camshaft Adjuster Leaks — Oil in Wiring Harness, Electric thermostat failure. Power: 184 PS.
C-Klasse (M274, 2014–2018) — Be Careful: High-Pressure Pump Faulty or Noisy, Camshaft Adjuster Leaks — Oil in Wiring Harness, Electric thermostat failure. Power: 211 PS.
C-Klasse (M276, 2014–2018) — Be Careful: Oil cooler leaking in the V-block, Camshaft adjuster leaking — wiring harness contaminated, Piston slap (early 3.5L variants). Power: 333 PS.
C-Klasse (M270DE16, 2015–2018) — Be Careful: Camshaft Adjuster Solenoid Leaks — Oil in Wiring Harness, Recall — Camshaft Break (Production Defect 2015), Electric Thermostat Failure. Power: 129 PS.
C-Klasse (M274, 2015–2018) — Be Careful: High-Pressure Pump Faulty or Noisy, Camshaft Adjuster Leaks — Oil in Wiring Harness, Electric thermostat failure. Power: 245 PS.
C-Klasse (M276, 2015–2018) — Be Careful: Oil cooler leaking in the V-block, Camshaft adjuster leaking — wiring harness contaminated, Piston slap (early 3.5L variants). Power: 367 PS.
C-Klasse (M177, 2015–2021) — Be Careful: MCT Gearbox — Clutch Wears in City Traffic, Camshaft Adjuster Solenoid Draws Oil into Wiring Harness, Camshaft Cover Gasket Leaking — Hot-V Area. Power: 476 PS.
C-Klasse (M177, 2015–2021) — Be Careful: MCT Gearbox — Clutch Wears in City Traffic, Camshaft Adjuster Solenoid Draws Oil into Wiring Harness, Camshaft Cover Gasket Leaking — Hot-V Area. Power: 510 PS.
C-Klasse (M274, 2015–2018) — Be Careful: High-Pressure Pump Faulty or Noisy, Camshaft Adjuster Leaks — Oil in Wiring Harness, Electric thermostat failure. Power: 211 PS.
C-Klasse (M264, 2019–2021) — Be Careful: Exhaust Valves Defective — Cylinder Head Damage (Serial Defect), HV Cables and E-Motor Integration Defective (PHEV), Chain Tensioner Loses Tension — Chain Rattling. Power: 204–211 PS.
C-Klasse (OM654, 2019–2021) — Be Careful: Rocker Arm and Camshaft Wear, Electric Coolant Pump Leaking — Recall, NOx Sensor Defective — AdBlue Fault and Start Inhibit. Power: 194–200 PS.
What to watch out for with the Mercedes-Benz C-Klasse? See the detailed listing of all engine and vehicle weaknesses in the sections above.
Frequently Asked Questions
What problems and weaknesses does the Mercedes-Benz C-Klasse W205 have? +
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Last updated: February 2026 · All information without guarantee